I am a bit confused about what is required for arenas. In some places I can build Arenas in others I cannot. I thought it was connected to gov level, but I have type I cities that cannot build them. Some cities have game fields, and good gov, but no option to upgrade.

Some places have gyms, do these conflict with Arenas?

The Hippodrome has similar errors...

EDIT: I a somewhat related note: What is up with the not_here hidden_resource? I understand it is used to make certain buildings unbuildable to all factions (smiths), however there are alot of "and not hidden_resource not_here". However no province has not_here, so is this useless or some sort of trick?